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Published June 03, 2014, 11:52 AM

Mystery over pig virus origins contributes to spread and anxiety

Swine veterinarian Bill Minton thought the baby pigs dying at a farm in western Ohio had a bad case of gastro-enteritis and was stumped when lab results came back with no indication of what had killed them.

By: Tom Polansek, Reuters

CHICKASAW, Ohio — Swine veterinarian Bill Minton thought the baby pigs dying at a farm in western Ohio had a bad case of gastro-enteritis and was stumped when lab results came back with no indication of what had killed them.

It took nearly 30 days — and hundreds more pigs dying in five other states — for Minton to learn the farm was ground zero for a virulent, fast-spreading virus that had never been seen before in the U.S.

A year later, the disease, called Porcine Epidemic Diarrhea virus (PEDv), has wiped out an estimated 10 percent of the U.S. pig population, helped push pork prices to record highs, and raised questions about U.S. oversight of the livestock industry and measures designed to protect the nation’s food supply.

The U.S. Department of Agriculture still has no clear idea about how PEDv entered the country. With each passing day, veterinarians, hog producers and meat processors fear that other diseases might be finding the same pathway that allowed in PEDv.

“I know that people are concerned about the pathways and feel like we haven’t done enough,” says John Clifford, the USDA’s chief veterinary officer. “It’s hard. It’s like looking for a needle in a haystack.”

Veterinarians have criticized USDA for waiting a year to require farmers to report outbreaks to the government. The agency still has not laid out guidelines for compliance with the new requirement.

Clifford notes the agency at first deferred to international standards, which do not require mandatory reporting of PEDv cases. He declines to comment on when Agriculture Secretary Tom Vilsack will lay out details of the agency’s reporting requirements.

Vilsack and Clifford will face questions this week about their handling of PEDv at the World Pork Expo in Des Moines, Iowa, the industry’s largest annual gathering. Many expect the officials will use the event to say more about the requirements.

“We’re definitely asking USDA to prioritize really making it a full-fledged investigation,” says Liz Wagstrom, chief veterinarian for the National Pork Producers Council. “PEDv has really pointed out that we are vulnerable.”

Eric Neumann, a veterinarian studying the transmission of the disease, says the agency could have better tracked the spread of PEDv by insisting earlier that veterinarians report outbreaks. Some submitted voluntary reports on PEDv cases.

“USDA deserves some very fair criticism that they did not put a more visible effort into investigating what the original source of the virus was,” Neumann says.

By this point, mandatory reports might not help control PEDv because the disease has already spread to 30 states, researchers say. It might also be too late to figure out specifically how PEDv entered the country, they add.

“Just like a criminal case, the farther you get from an incident, the harder it is to put the pieces together,” Neumann says.

Mistaken diagnosis

The first known case in Ohio was not identified for weeks because Minton initially thought the virus was a different disease called Transmissible Gastro-enteritis (TGE). Veterinarians across the country drew the same conclusion when handling early outbreaks because PEDv had never before been seen in the United States.

Minton, a well-known veterinarian who logs 50,000 miles a year visiting farms in his white pick-up truck, realized he had treated the first case when he re-tested fecal samples from the Ohio farm after USDA confirmed PEDv was in the country.

Minton initially suspected the farm with the first known PEDv case got it from a contaminated truck that came from a slaughterhouse. Since then, though, he has started considering animal feed as a suspect.

“If something like this can get in, we’re not going to stop the next one,” he says of PEDv. “We’ve got to continue to protect our food supply.”

Researchers in the past year have learned that PEDv, which causes diarrhea and vomiting, thrives in cold, damp conditions and likely originated in Anhui province in China. It can be transmitted from pig to pig, by contact with pig manure and from farm to farm on trucks. Farms can suffer more than one outbreak of the disease, meaning eradication may prove more difficult than many first assumed.

Tracking outbreaks

Early PEDv outbreaks occurred around the country at some farms unconnected by trucks, personnel or animals, according to researchers. It seems common sense then to consider that PEDv may have been carried by animal feed or feed ingredients like vitamins, Wagstrom says.

Following the initial outbreaks, USDA and industry members identified seven feed-related risk factors that could have a possible relationship with the entry of PEDv into the U.S. But little progress has been made to nail down a carrier, according to veterinarians.

USDA launched a general review in late 2013 of how swine viruses enter the country. It does not focus on PEDv but Clifford says the virus would have entered in the same manner as other diseases.

Initial results indicate it is more likely for people than feed to carry in hog diseases because viruses in feed often die during long trips on hot cargo ships, says Lisa Ferguson, national director of policy permitting and regulatory services for USDA’s Animal and Plant Health Inspection Service. One way humans can transmit the virus is on their shoes.

The U.S. Food and Drug Administration, which is responsible for ensuring the safety of animal feed, is reviewing the manufacturing process of one company that produces dried pig plasma used as a feed supplement, a spokeswoman says. Still, none of the U.S. testing has established that any PEDv particles were still active when they were used in feed. The FDA declined to identify the company under review.

Lack of understanding about the transmission of PEDv has created a palpable fear throughout the U.S. pork industry.

Duane Stateler, a pig farmer who is president of the Ohio Pork Council, says a local farm supply store requested that he stay away after his pigs caught PEDv. Instead, the store sent an employee to deliver goods to Stateler in the parking lot of a bowling alley 1/4-mile from the store. Separately, he spent $500 on sandals for himself and his employees so they only wear certain shoes in certain parts of the farm.

“It’s almost like you keep looking over your shoulder all the time,” he says.